The mammalian target of rapamycin (mTOR) is a central cell growth regulator that integrates a wide range of growth stimulating and inhibitory signals. mTOR inhibitors are FDA approved drugs for immunosuppression in organ transplantation and cancer treatment. The mTOR kinase forms two complexes, TORC1 and TORC2, with distinct subunit composition and physiological functions. In response to growth factors and nutrients, TORC1 promotes cell growth by stimulating translation. Overwhelming evidence has also demonstrated a key role of TORC1 in inhibiting autophagy. However, the molecular mechanism of TORC1 in autophagy regulation is unknown. The AMP activated protein kinase (AMPK) is a key cellular energy sensor and functions to maintain cellular energy homeostasis. AMPK has been implicated in autophagy induction, yet little is known about the mechanism of AMPK in regulating the autophagy machinery. Our preliminary studies indicate that TORC1 and AMPK can regulate key components of the autophagy machinery by direct phosphorylation. The long-term goal of this project is to elucidate the molecular mechanisms of TORC1 and AMPK in induction of autophagy in response to nutrient signals. The specific aims for this proposal are: 1 To elucidate the functional significance of ULK1 phosphorylation by TORC1 in autophagy 2 To determine the mechanism of AMPK in regulating ULK1 activation and function in autophagy 3 To investigate the mechanism of AMPK in VPS34 regulation during autophagy